Saw Gin Cotton Processing

Saw gin stands use 80–170 circular saw blades (8–12 inch diameter, 18–20 teeth/inch, rotating at 400–600 rpm) on a single shaft to comb lint fibres from seed cotton fed across a seed roll. Saw teeth protrude through a ribbed ginning bar (rib spacing 3/16–5/16 inch) that retains seeds while lint is carried forward. Lint is removed from saws by high-velocity air (doffer section at 1,500–3,000 m/min) or mechanical brush. Throughput of 10–18 bales (500 lb each) per hour per gin stand. Processing at 10–12% seed cotton moisture content is optimal; above 14% causes lint winding on saws and below 8% increases fibre breakage by 10–20%. Gin speed increase of 100 rpm raises throughput 8–10% but increases short fibre content (SFC) by 0.5–1.5% and nep generation by 15–25 neps/g. Used exclusively for G. hirsutum upland varieties.